Brazil goalkeeper Julio Cesar has joined Benfica on a two-year deal after being released by QPR.
The 19-year-old has broken into Oscar Garcia's first team this season and made 23 appearances to help the Seagulls into the play-off picture.
He told the club website: "I'm really excited; hopefully it's going to be a good four years with the new training ground and the club pushing for promotion.
"The staff are working hard behind the scenes to get the best young players and hopefully more of us can come through from the Academy to the first team.
"A new contract does bring security, but we've got to keep moving forward. The main aim is to get promotion, so hopefully we can do that in the next few years.
"Being a Premier League player is the ultimate aim for any footballer, so hopefully we can get there soon."